We'll I'm not going to argue with the sharpness. It's insane (at 1600 no less!). I can only really afford one zoom and I am tempted to ditch my 70-200 F4 IS and get the 100-400 based on results like I am seeing here. I always thought the 70-200's were a little sharper, but this has me thinking... Are these results typical for this lens?

Absolutely. Here's a random one I pulled out of my gallery taken with that lens. It's quite sharp, though still a bit short of what a 400 prime can do. I've been quite happy with it. BTW, your 70-200 f/4 is one of the sharper zooms that Canon makes, though it's a bit short for wildlife, as I'm sure you know. The f/2.8 version, while pretty heavy, can be nicely paired with a 2x extender at the expense of a stop or two (can't recall) and give you the best of both worlds.